This invention provides for the sharpening of chain saw cutter situated on a saw chain with a round file or file holder without removing the saw chain from the saw bar. During normal use chain saw cutters become dull and frequently require resharpening. Accuracy and sometimes speed in sharpening is essential.
During cutting operation this endless saw chain is pulled along an elongated chain saw bar in a circular manner by a chain saw sprocket and saw chain teeth. The saw chain includes alternate right hand and left hand cutters spaced about 11/8 inches apart and situated slightly off center. The standard saw chain has an outside width of about 5/32 of an inch. With rivet heads the width is about 3/16 of an inch. The right hand and left hand cutters extend outward beyond the chain approximately 1/16 of an inch each. The saw chain includes a center link of teeth for pulling which extend into a groove in the saw bar. These teeth are slightly less than 1/16 of an inch in width, and the saw groove is slightly more than 1/16 of an inch in width. The outside width of the saw bar is approximately 5/32 of an inch. The saw cutters have a top plate horizontal cutting edge, and a side plate vertical cutting edge. The filing angles of these cutters recommended by manufacturers is usually 30 degrees or 35 degrees, with some cutters requiring an upward pitch of 10 degrees. Occasionally, some operators like to file cutters to 40 degree angles. The round file sizes recommended by manufacturers of saw chains are either 5/32, 3/16, or 7/32 of an inch in diameter.